Hydrodearylation of Heavy Aromatics via Dissolved Hydrogen
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Solution Overview
Problem
Conventional three-phase hydrocarbon processing systems are limited in their ability to effectively perform hydrodearylation on heavy hydrocarbon feeds, particularly those containing non-condensed aromatic molecules with two or more aromatic rings bridged by an alkyl group, leading to catalyst deactivation and reduced production of valuable aromatics like benzene and xylenes.
Innovation Solution
A two-phase liquid-solid system where hydrogen is dissolved in the liquid hydrocarbon feedstock, eliminating the need for a separate hydrogen gas phase, and using a catalyst bed with specific metal components like nickel, molybdenum, and zeolite to facilitate hydrodearylation reactions at temperatures between 200°C to 450°C, converting alkyl-bridged multi-aromatics into mono-aromatics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional three-phase hydrocarbon processing systems are used for hydrodearylation of heavy hydrocarbon feeds, then the process can handle multi-aromatic molecules, but catalyst deactivation occurs rapidly leading to reduced productivity
Solution Approach 1:
The patent changes the physical state parameters of hydrogen from gaseous to dissolved state in the liquid hydrocarbon phase. This parameter change allows hydrogen to be uniformly distributed throughout the liquid phase, enabling effective contact with the catalyst surface without requiring a separate gas phase, thereby maintaining high productivity while preventing catalyst deactivation
Solution Approach 2:
The patent extracts the gaseous hydrogen phase from the conventional three-phase system, eliminating the gas/liquid interface and direct gas-catalyst contact. By dissolving hydrogen in the liquid phase, the system removes the harmful direct interaction between gaseous hydrogen and the catalyst that causes rapid deactivation, while still enabling the necessary hydrodearylation reactions
2Productivity
If high temperatures greater than 400°C are used in TA/TDP units to process toluene and C9/C10 aromatics, then benzene and xylene production increases, but catalyst deactivation accelerates
Solution Approach 1:
The patent employs parameter changes by dissolving hydrogen in the liquid phase and conducting reactions at moderate temperatures (200-400°C) rather than the conventional high temperatures (>400°C). This temperature parameter change, combined with the dissolved hydrogen approach, maintains high productivity while significantly extending catalyst lifetime by preventing thermal and chemical deactivation
3Object-affected harmful factors
If heavy compounds are removed from mixed xylenes by fractionation, then olefinic material is eliminated, but valuable C6-C8 aromatics are lost as lower value fuels
Solution Approach 1:
The patent changes the chemical state of heavy compounds by converting multi-aromatic molecules into mono-aromatic molecules through hydrodearylation. This parameter change transforms the molecular structure rather than simply separating by boiling point, allowing recovery of valuable C6-C8 aromatics that would otherwise be lost in fractionation while still eliminating harmful olefinic material
Solution Approach 2:
The patent converts the harmful effect of heavy multi-aromatic compounds (which cause catalyst deactivation and require removal) into a beneficial outcome. By using these heavy compounds as feedstock for hydrodearylation, the process transforms them into valuable mono-aromatic products, turning a waste removal problem into a value-added production opportunity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the production of C6-C8 aromatics, improves the suitability of heavy aromatics for blending, and extends the catalyst life by avoiding deactivation, thereby enhancing the overall efficiency and quality of hydrocarbon processing.
Implementation Method 1
A two-phase liquid-solid system where hydrogen is dissolved in the liquid hydrocarbon feedstock
Implementation Method 2
using a catalyst bed with specific metal components like nickel, molybdenum, and zeolite to facilitate hydrodearylation reactions
Implementation Method 3
The hydrogen gas adsorbs at an active site on the catalyst surface. Liquid molecules are transported to the external surface of the catalyst, and then diffuse into the pores of the solid catalyst and adsorb on the surface
Data Source
AI summary
Systems and methods for hydrodearylation of a hydrocarbon feed stream comprising non-condensed alkyl-bridged multi-aromatic hydrocarbons, the method including supplying a hydrogen feed to the hydrocarbon feed stream comprising non-condensed alkyl-bridged multi-aromatic hydrocarbons; mixing the hydrogen feed with the hydrocarbon feed stream to saturate the hydrocarbon feed stream with hydrogen gas to create a hydrogen-enriched liquid hydrocarbon stream; passing the hydrogen-enriched liquid hydrocarbon stream to a hydrodearylation reactor without a separate gaseous phase of hydrogen; allowing the hydrogen-enriched liquid hydrocarbon stream to react in presence of a catalyst under specific reaction conditions to produce a product stream comprising a reduced concentration of di-aromatic compounds and an increased concentration of mono-aromatic compounds compared to the hydrocarbon feed stream comprising non-condensed alkyl-bridged multi-aromatic hydrocarbons; and recovering, from the hydrodearylation reactor, a product stream for a downstream process, wherein the non-condensed alkyl-bridged multi-aromatic hydrocarbons include at least two benzene rings connected by an alkyl bridge group having at least two carbons, wherein the benzene rings are connected to different carbons of the alkyl bridge group.